B & J wrote:

Did you plant them in full sun? Many impatiens varieties do not like sun,
particularly the double varieties, although there are a number of single
varieties that handle sunlight quite well. I had a double variety that did
well in shade but had the buds dry up and fell off in sunlight.

I had the exact opposite experience. I had no luck at all raising
double impatiens in a shady corner of my garden. Someone at a garden
center told me they needed more light, so I moved a near-moribund plant
to a mostly sun location and it is now completely covered with flowers.